Interleukin-4-carrying small extracellular vesicles with a high potential as anti-inflammatory therapeutics based on modulation of macrophage function.

Interleukin-4 (IL4), a Th2-type cytokine that can drive M2 macrophage polarization, is expected to be used as an anti-inflammatory therapy agent as M2 polarization of macrophages can ameliorate chronic inflammation. However, several problems, such as the low effectiveness and side effects, have hampered the clinical application. To safely and effectively use IL4, an efficient delivery of IL4 to target cells, macrophages, is necessary. Small extracellular vesicles (sEVs) are promising candidates as macrophage delivery carriers because they are efficiently recognized by macrophages. In addition, considering the property of IL4 signaling, for which the internalization of IL4 receptor into the cellular compartment is important, and sEV uptake mechanism by macrophages, sEVs are expected to amplify IL4 signaling. In this study, we developed IL4-carrying sEVs (IL4-sEVs) by genetically engineering sEV-producing cells. We investigated the bioactivity of IL4-sEVs using RAW264.7 macrophages and their potential for therapeutic application to the treatment of an inflammatory disease using collagen-induced arthritis model mice. IL4-sEVs exhibited stronger anti-inflammatory effects on M1-polarized macrophages through M2 polarization of macrophages than those of soluble IL4 proteins. Moreover, IL4-sEVs exhibited more effective therapeutic effects on rheumatoid arthritis than those of IL4. These results indicate that IL4-carrying sEVs are promising anti-inflammatory therapeutics.